Since people often work on multiple documents and perform many operations on them, it would be nice to have one command that allows you to save all of them at once.

In any case, when you get the warning that you are about to close Acrobat and there are many files with unsaved changes, instead of having a prompt for each and every one, you should be able to click on a checkmark that says "apply to all documents," like you have in Word.

Thanks!